Several protocols are known to exist for passing a caller's phone number and the called phone number between a customer's Private Branch Exchange (PBX) and a phone network. By example, one network provider offers Integrated Services Digital Network (ISDN) in-band ANI services that provide combinations of Automatic Number Identification (ANI), that is the caller's billing number, and Dialed Number Identification Service (DNIS) providing up to the last seven digits of the called number. The ANI and DNIS information is provided in-band to PBXes in order to identify the caller and to identify what services were dialed by the caller. However, to use this protocol for in-band ANI and/or DNIS PBX vendors are required to create interfaces for the protocol such that PBXes may employ this information to provide routing, queuing priority, and intelligent answering capabilities. One problem in creating such an interface relates to a requirement that existing PBXes be modified, such as by providing new software, in order to collect the ANI and DNIS information. Such modifications are generally undesirable both from a customer's and a vendor's viewpoint.
It is thus one object of the invention to provide a novel protocol that requires only network protocol changes in order to enable existing PBXes to receive ANI and DNIS and provide this valuable information to customer business applications.
It is another object of the invention to provide method and apparatus that, in response to an incoming call, returns a call accepted signal to a network and transmits DTMF-encoded ANI and/or DNIS signals over a T1 trunk group to and through a PBX, the transmitted information being expressive of ANI and/or DNIS information.